From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 43767E74AC4 for ; Tue, 3 Dec 2024 16:51:32 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 67B3B6B0085; Tue, 3 Dec 2024 11:51:31 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 629626B0088; Tue, 3 Dec 2024 11:51:31 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 53F266B008A; Tue, 3 Dec 2024 11:51:31 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0013.hostedemail.com [216.40.44.13]) by kanga.kvack.org (Postfix) with ESMTP id 36CF16B0085 for ; Tue, 3 Dec 2024 11:51:31 -0500 (EST) Received: from smtpin27.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay09.hostedemail.com (Postfix) with ESMTP id 9FC3D80AC4 for ; Tue, 3 Dec 2024 16:51:30 +0000 (UTC) X-FDA: 82854238110.27.39F0451 Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) by imf24.hostedemail.com (Postfix) with ESMTP id DE33618001B for ; Tue, 3 Dec 2024 16:51:26 +0000 (UTC) Authentication-Results: imf24.hostedemail.com; dkim=pass header.d=infradead.org header.s=casper.20170209 header.b=kcUGLwD9; spf=none (imf24.hostedemail.com: domain of willy@infradead.org has no SPF policy when checking 90.155.50.34) smtp.mailfrom=willy@infradead.org; dmarc=none ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1733244682; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=PEy0xzOQmFtsAubHZhQVUKPelhUO+CET1Kndu3/TO0Q=; b=BUVh+1Y8PrJHdBCVYno9iVYkTrmnOHcHpoKXvlQqHKFUR0H1ySfsohwUzifT1fKCk2RLKT pGhj9hzepXsI7Iw8qCufExp5LvNwcA5zLPa03QsXJkcEogXJ2RrETAYbzEPmCRhv8VRr+u attdfvRSUOZ3O9gqZ1yfBONYW0xNFBk= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1733244682; a=rsa-sha256; cv=none; b=UY53YH1DI8dtoQFN6T1yLQY/8bRQlFze4MAUz4QTfgrdOzFwduzyxsh5BhJhBEPYM9Im0/ IsoQNFvuZ20BCDiyNA1UGyIqUOQ1YCjtgZMUF/g8+nuvivAdBDECD1Y6RYL3XcN09HqfUf 7hQgWVG9sBuWKpb8CRjAdT7M4r+jdrE= ARC-Authentication-Results: i=1; imf24.hostedemail.com; dkim=pass header.d=infradead.org header.s=casper.20170209 header.b=kcUGLwD9; spf=none (imf24.hostedemail.com: domain of willy@infradead.org has no SPF policy when checking 90.155.50.34) smtp.mailfrom=willy@infradead.org; dmarc=none DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=PEy0xzOQmFtsAubHZhQVUKPelhUO+CET1Kndu3/TO0Q=; b=kcUGLwD98U7AV/Nx0H5iKyc5Vw i026TX4gLqkLN/uUGMLL9wAAcjFtQQMYdFV2QvplzBVL3/V44L6m+K7QLIZNyX+QJ+8csOUfjERw2 xcltDx4Tais1TCq4Ghij1vUbEnC0Yoa/UVoJhsfkBNotA0toN3gfMIf8NvamjE0E0Gtpj3zUCHKG1 kO/WpI5OyjrYbd4PqlChIMsyLLocsYi5KhOt2WQVp7GVMHeneKeAY/FH8Pqqc0Ej3kqxwYfwvrIe/ 4nW1ke4TKXUzr/Ca5tp+6+4ODd7njjmVKTvMG3B1DNdF0bZwnlZqv8WqT200d5mq8mf45WixZCcpI O3fi/6NA==; Received: from willy by casper.infradead.org with local (Exim 4.98 #2 (Red Hat Linux)) id 1tIW7M-00000009tWb-2F0h; Tue, 03 Dec 2024 16:51:20 +0000 Date: Tue, 3 Dec 2024 16:51:20 +0000 From: Matthew Wilcox To: alexs@kernel.org Cc: Vitaly Wool , Miaohe Lin , Andrew Morton , linux-kernel@vger.kernel.org, linux-mm@kvack.org, minchan@kernel.org, senozhatsky@chromium.org, david@redhat.com, 42.hyeyoo@gmail.com, Yosry Ahmed , nphamcs@gmail.com Subject: Re: [PATCH v7 01/21] mm/zsmalloc: add zpdesc memory descriptor for zswap.zpool Message-ID: References: <20240902072136.578720-1-alexs@kernel.org> <20240902072136.578720-2-alexs@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20240902072136.578720-2-alexs@kernel.org> X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: DE33618001B X-Stat-Signature: 8ej9cxc7oets1kuhy8t9uzk9hpjoi6pm X-Rspam-User: X-HE-Tag: 1733244686-254386 X-HE-Meta: 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 qfy3gocd OGSuHnwrcgKK5V9k2k8BrYhefwWy29a/lDaVOJ28PAjFtPesNmZaNFDzUHC5Z84Sm9f1SjgUS0y32yxosPVz+fPMMx5P1M4gBgg0MlZx73s9SE8YUW2D4roH2lR3pxlnBHUJxBK9uT1I4sA7M3vK5V9kuSJKgCn1u4Rl3oE9G84OHuJek7RJLFpXEVFrTDIxE1jHQ5xhq+XzHhwKJQT349gVynDVGrDdvzab8Vlk9jdqYujKN2td81VnOlIoSTSzxDsT26/9fT+ViZhiyLbHCa61h0kj40wqapkX7wQq3Y4dyFvQ7nrRcLY3yYDQII8PDaEz6pUjsF8NgDaw= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon, Sep 02, 2024 at 03:21:12PM +0800, alexs@kernel.org wrote: > And keep the memcg_data member, since as Yosry pointed out: > "When the pages are freed, put_page() -> folio_put() -> __folio_put() > will call mem_cgroup_uncharge(). The latter will call folio_memcg() > (which reads folio->memcg_data) to figure out if uncharging needs to > be done. ... why does that mean we need to keep memcg_data in this definition? If it's unused, it will stay unused. > There are also other similar code paths that will check > folio->memcg_data. It is currently expected to be present for all > folios. So until we have custom code paths per-folio type for > allocation/freeing/etc, we need to keep folio->memcg_data present and > properly initialized." ... > +struct zpdesc { > + unsigned long flags; > + struct list_head lru; > + struct movable_operations *mops; Hm. I'm not sure this is a wise definition. While yes, we know it will only point to the mops, we always set the bottom two bits to '10'. So I think it's safer to make this 'unsigned long mops' and force people to _not_ use it directly.